1. Field of the Invention
The present invention relates to a multilayered printed wiring board, e.g., which is employed as a module board in a portable device and a method for manufacturing the multilayered printed wiring board.
2. Description of the Related Art
Recently, the downsizing and the weight saving for a portable device such as a cellular phone are developed and moreover, the performance of the portable device is developed. In this case, a multilayered printed wiring board is employed as the module board in the portable device. In view of the above-described requirements for portable device, it is desired to downsize, thin and grow in density the multilayered printed wiring-board while an area to mount some electric/electronic components is maintained.
In this point of view, a built-in component type wiring board is proposed in Reference 1 wherein one or more micro chips such as 0402 chip and 0603 chip are built in so as to enhance the reliability of the micro chip(s). According to the built-in component type wiring board, the packaging density of component for the module board can be enhanced so that the module board can be downsized.
Moreover, one or more depressed portions are formed at a multilayered printed wiring board so that some electric/electronic components are housed in the corresponding depressed portions (see, Reference 2). In this case, the total thickness of the multilayered printed wiring board can be reduced. Referring to Reference 2, the bottom printed wiring board and the top printed wiring board are prepared, and some components are mounted on the bottom printed wiring board and some openings are formed at the top printed wiring board so that the components can be inserted into the openings at the laminating using an adhesive resin sheet. In this case, the components are surrounded by a resin.
[Reference 1] JP-A 2004-134424 (KOKAI)
[Reference 2] JP-A 2005-32739 (KOKAI)
However, the electric/electronic component(s) may generate heat. Therefore, when the electric/electronic component(s) is (are) built in, the thus obtained built-in component type wiring board may exhibit some disadvantages due to the heat from the electric/electronic component(s). Moreover, in the built-in component type wiring board, the electric/electronic component(s) can not be wire-bonded. Also, it is desired that the electric/electronic component(s) are inserted in the corresponding depressed portion(s) (cavity (cavities)) so as to reduce the total thickness of the board.
As of now, it is desired that various electric/electronic components are mounted on the module board so that the module board must satisfy various requirements. For example, the module mode is configured so as to embed the components therein, mount the component on the main surface or insert the components in the corresponding depressed portions (cavities) in view of the sizes and shapes of the components.